全部 标题 作者
关键词 摘要

OALib Journal期刊
ISSN: 2333-9721
费用:99美元

查看量下载量

相关文章

更多...
科学通报  2012 

西藏纳木错全新世沉积物的环境磁学参数变化机理

, PP. 2980-2990

Keywords: 湖泊沉积,岩石磁学,纳木错,青藏高原,全新世

Full-Text   Cite this paper   Add to My Lib

Abstract:

青藏高原的高分辨环境记录对于理解全球气候与环境变化至关重要.湖泊沉积物的磁学参数能够记录沉积环境和古气候信息.纳木错是西南季风过渡区大湖的典型代表,前人在该湖开展了大量地球化学、微体化石、沉积学和生物化学分析,极大地推动了该区古气候环境的重建工作.但迄今为止,还缺乏对纳木错湖泊沉积物系统的环境磁学研究.因此,本文选取纳木错湖芯NC08/01孔全新世以来(11.3calkaBP)的湖泊沉积物进行详细的岩石磁学与环境磁学研究,结合地球化学指标,在明确的气候背景下探讨该湖沉积物磁性参数的变化机制.结果表明,纳木错全新世沉积物的磁性参数受到陆源磁性矿物输入、还原溶解作用和磁细菌活动的共同影响.根据各磁学参数系统的变化趋势,可将该研究段样品分为3段第Ⅰ段(236~199cm,11.3~7.8calkaBP)主要载磁矿物为粗颗粒磁铁矿,粒度均一,含量较高,并与Ti含量呈正相关关系,指示该段磁性矿物受后期溶解作用影响较小,其含量主要反映物源输入信息;第Ⅱ段(198~102cm,7.8~2.1calkaBP),磁性矿物颗粒变细,含量明显降低.在该段,湖面下降,水动力减小,进而输入的磁性矿物粒径也减小,容易受到后期溶解作用的影响;第Ⅲ段(101~0cm,2.1~0calkaBP),磁性矿物以生物成因单畴磁铁矿和陆源碎屑成因磁铁矿为主,磁性颗粒含量的变化与Ti含量不相关.以上结果表明,在弱还原环境中,湖泊沉积物磁性矿物的保存状态及磁学性质与其初始粒径密切相关.通过对磁性矿物信息的系统研究(包括粒径和含量变化等)并结合陆源输入指标(如Ti含量),能够较为准确地反映湖泊环境氧化还原程度的变化.以上结果为正确解译该湖沉积物的环境磁学指标提供了基础.

References

[1]  3 Zhu L P, Wu Y H, Wang J B, et al. Environmental changes since 8.4 ka reflected in the lacustrine core sediments from Nam Co, central Tibetan Plateau, China. Holocene, 2008, 18: 831-839
[2]  5 Evans M E, Heller F. Environmental Magnetism: Principles and Applications of Environmagnetics. New York: Academic Press, 2003
[3]  8 Zhu L P, Zhang P Z, Xia W L, et al. 1400-year cold/warm fluctuations reflected by environmental magnetism of a lake sediment core from the Chen Co, southern Tibet, China. J Paleolimn, 2003, 29: 391-401??
[4]  9 Mischke S, Zhang C J. Holocene cold events on the Tibetan Plateau. Global Planet Change, 2010, 72: 155-163??
[5]  10 Mann S, Sparks N H C, Frankel R B, et al. Biomineralization of ferrimagnetic greigite (Fe3S4) and iron pyrite (FeS2) in a magnetotactic bacterium. Nature, 1990, 343: 258-261??
[6]  11 Jelinowska A, Tucholka P, Wieckowski K. Magnetic properties of sediments in a Polish lake: Evidence of a relation between the rock-magnetic record and environmental changes in Late Pleistocene and Holocene sediments. Geophys J Int, 1997, 129: 727-736??
[7]  13 Stockhausen H, Thouveny N. Rock-magnetic properties of Eemian maar lake sediments from Massif Central, France: A climatic signature? Earth Planet Sci Lett, 1999, 173: 299-313
[8]  14 王利强, 易朝路, Schütt B, 等. 青藏高原纳木错湖阶沉积的发生特征及环境指示意义. 沉积学报, 2009, 3: 503-510
[9]  16 Frenzel P, Wrozyna C, Xie M P, et al. Palaeo-water depth estimation for a 600-year record from Nam Co (Tibet) using an ostracod-based transfer function. Quat Int, 2010, 218: 157-165??
[10]  18 林晓, 朱立平, 汪勇, 等. 西藏纳木错湖芯正构烷烃及其反映的8.4 ka以来的环境变化. 科学通报, 2008, 53: 2352-2357
[11]  19 Zhu L P, Peng P, Xie M P, et al. Ostracod-based environmental reconstruction over the last 8400 years of Nam Co Lake on the Tibetan plateau. Hydrobiologia, 2010, 648: 157-174??
[12]  21 Wang J B, Zhu L P, Daut G, et al. Investigation of bathymetry and water quality of Lake Nam Co, the largest lake on the central Tibetan Plateau, China. Limnology, 2009, 10: 149-158??
[13]  24 Liu Q S, Roberts A P, Torrent J, et al. What do the HIRM and S-ratio really measure in environmental magnetism? Geochem Geophys Geosys, 2007, 8: Q09011, doi: 10.1029/2007GC001717
[14]  25 Roberts A P, Pike C R, Verosub K L. First-order reversal curve diagrams: A new tool for characterizing the magnetic properties of natural samples. J Geophys Res, 2000, 105: 28461-28475??
[15]  26 Harrison R J, Feinberg J M. FORCinel: An improved algorithm for calculating first-order reversal curve distributions using locally weighted regression smoothing. Geochem Geophys Geosys, 2008, 9: Q05016, doi: 10.1029/2008GC001987??
[16]  30 Roberts A P. Magnetic properties of sedimentary greigite (Fe3S4). Earth Planet Sci Lett, 1995, 134: 227-236??
[17]  31 Verwey E J. Electronic conduction of magnetite (Fe3O4) and its transition point at low temperature. Nature, 1939, 144: 327-328
[18]  32 Roberts A P, Chang L, Rowan C J, et al. Magnetic properties of sedimentary greigite (Fe3S4): An update. Rev Geophys, 2011, 49: RG1002, doi: 10.1029/2010RG000336
[19]  34 Li J H, Pan Y X, Chen G J, et al. Magnetite magnetosome and fragmental chain formation of Magnetospirillum magneticum AMB-1: transmission electron microscopy and magnetic observations. Geophys J Int, 2009, 177: 33-42??
[20]  35 Dunlop D J. Theory and application of the Day plot (Mrs/Ms versus Hcr/Hc). 1. Theoretical curves and tests using titanomagnetite data. J Geophys Res, 2002, 107, doi: 10.1029/2001JB000486
[21]  36 Nowaczk N R, Harwart S, Melles M. A rock magnetic record from Lama Lake, Taymyr Peninsula, northern Central Siberia. J Paleolimn, 2000, 23: 227-241??
[22]  37 Nowaczyk N R. Dissolution of titanomagnetite and sulphidization in sediments from Lake Kinneret, Israel. Geophys J Int, 2011, 187: 34-44??
[23]  38 Berner R A. Sedimentary pyrite formation: An update. Geochim Cosmochim Acta, 1984, 48: 605-615??
[24]  39 Canfield D E, Raiswell R, Bottrell S. The reactivity of sedimentary iron minerals toward sulfide. Am J Sci, 1992, 292: 659-683??
[25]  40 Poulton S W, Krom M D, Raiswell R. A revised scheme for the reactivity of iron (oxyhydr)oxide minerals towards dissolved sulfide. Geochim Cosmochim Acta, 2004, 68: 3703-3715??
[26]  41 Williamson D, Jelinowska A, Kissel C, et al. Mineral-magnetic proxies of erosion/oxidation cycles in tropical maar-lake sediments (Lake Tritrivakely, Madagascar): Paleoenvironmental implications. Earth Planet Sci Lett, 1998, 155: 205-219??
[27]  42 Berner R A. Early Diagenesis: A Theoretical Approach: Princeton University Press. 1980
[28]  1 Qiu J. The third pole. Nature, 2008, 454: 393-396??
[29]  2 Gasse F, Arnold M, Fontes J C, et al. A 13000-year climate record from western Tibet. Nature, 1991, 353: 742-745??
[30]  4 Bond G, Showers W, Cheseby M, et al. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science, 1997, 278: 1257-1266??
[31]  6 Tudryn A, Tucholka P, Gibert E, et al. A late Pleistocene and Holocene mineral magnetic record from sediments of Lake Aibi, Dzungarian Basin, NW China. J Paleolimn, 2010, 44: 109-121??
[32]  7 Thouveny N, Debeaulieu J L, Bonifay E, et al. Climate variations in Europe over the past 140 kyr deduced from rock magnetism. Nature, 1994, 371: 503-506??
[33]  12 胡守云, 王苏民, Appel E, 等. 呼伦湖湖泊沉积物磁化率变化的环境磁学机制. 中国科学D辑: 地球科学, 1998, 28: 334-339
[34]  15 Doberschütz S, Frenzel P, Haberzettl T, et al. Monsoonal forcing of Holocene paleoenvironmental change on the Central Tibetan Plateau inferred from a lacustrine record of Lake Nam Co (Xizang, China). J Paleolimn, 2012
[35]  17 Keil A, Berking J, Mügler I, et al. Hydrological and geomorphological basin and catchment characteristics of Lake Nam Co, South-Central Tibet. Quat Int, 2010, 218: 118-130??
[36]  20 关志华, 陈传友, 区裕雄, 等. 西藏河流与湖泊. 北京: 科学出版社, 1984. 176-182
[37]  22 朱大岗, 孟宪刚, 赵希涛, 等. 西藏纳木错地区第四纪环境演变. 北京: 地质出版社, 2004. 13-17
[38]  23 Kasper T, Haberzettl T, Doberschütz S, et al. Indian Ocean Summer Monsoon (IOSM)-dynamics within the past 4 ka recorded in the sediments of Lake Nam Co, central Tibetan Plateau (China). Quat Sci Rev, 2012, 39: 73-85??
[39]  27 Liu Q S, Deng C L, Yu Y J, et al. Temperature dependence of magnetic susceptibility in an argon environment: Implications for pedogenesis of Chinese loess/palaeosols. Geophys J Int, 2005, 161: 102-112??
[40]  28 Lowrie W. Identification of ferromagnetic minerals in a rock by coercivity and unblocking temperature properties. Geophys Res Lett, 1990, 17: 159-162??
[41]  29 Roberts A P, Pillans B J. Rock magnetism of lower/middle Pleistocene marine sediments, Wanganui Basin, New Zealand. Geophys Res Lett, 1993, 20: 839-842??
[42]  33 ?zdemir ?, Dunlop D J. Hallmarks of maghemitization in low-temperature remanence cycling of partially oxidized magnetite nanoparticles. J Geophys Res, 2010, 115: B02101
[43]  43 Li Q, Lu H Y, Zhu L P, et al. Pollen-inferred climate changes and vertical shifts of alpine vegetation belts on the northern slope of the Nyainqentanglha Mountains (central Tibetan Plateau) since 8.4 kyr BP. Holocene, 2011, 21: 939-950
[44]  44 Egli R, Chen A P, Winklhofer M, et al. Detection of noninteracting single domain particles using first-order reversal curve diagrams. Geochem Geophys Geosys, 2010, 11: Q01Z11, doi: 10.1029/2009GC002916

Full-Text

Contact Us

service@oalib.com

QQ:3279437679

WhatsApp +8615387084133